title: Vitamin D, parathyroid hormone and muscle impairment in myotonic dystrophies.
abstract: Parathyroid function in Myotonic Dystrophy (DM) patients has been poorly investigated. Parathyroid and muscle parameters were assessed in 31 male DM1 (44±2 years), 13 male DM2 (56±2 years) and 32 healthy controls. Hyperparathyroidism was diagnosed in 18% of patients without differences between DM types. In all DM patients, hyperparathyroidism was associated with normocalcemia but one with hypercalcemia. DM patients presented significantly higher PTH and lower vitamin D (25OHD) compared with controls, also considering seasonality. Severe vitamin D deficiency (25OHD<10 ng/ml) was diagnosed in 40% and hypovitaminosis D (25OHD<30 ng/ml) occurred in 88% of DM patients. About one-third of DM1 presented hypophosphatemia associated with elevated PTH levels. Serum 25OHD levels negatively correlated with PTH and with body fat mass. Considering DM1 patients, serum PTH levels positively correlated with CTG triplet repeats. Furthermore, PTH levels negatively correlated with total modified Medical Research Council (MRC) and positively with Muscular Impairment Rating Scale (MIRS). By contrast, in DM2 patients muscle assessment did not show any correlation with parathyroid function. In conclusion, we arrived at the following: 1) severe vitamin D deficiency is common in DM patients and it is associated with secondary hyperparathyroidism; 2) primary hyperparathyroidism, though rare, may occur; 3) increased adiposity in DM may be a risk factor for hypovitaminosis D; and 4) high serum PTH levels may indicate a muscle impairment, at least in DM1.
authors.affiliation: Endocrinology and Diabetology Unit, Dept. of Biomedical Sciences for Health, University of Milan, Milan, Italy. elenapasseri83@libero.it
authors.forename: E
authors.initials: E
authors.lastname: Passeri
authors.forename: E
authors.initials: E
authors.lastname: Bugiardini
authors.forename: V A
authors.initials: VA
authors.lastname: Sansone
authors.forename: R
authors.initials: R
authors.lastname: Valaperta
authors.forename: E
authors.initials: E
authors.lastname: Costa
authors.forename: B
authors.initials: B
authors.lastname: Ambrosi
authors.forename: G
authors.initials: G
authors.lastname: Meola
authors.forename: S
authors.initials: S
authors.lastname: Corbetta
mesh_terms: D000328:Adult; D015992:Body Mass Index; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology; D009223:Myotonic Dystrophy / Q000097:blood / Q000150:complications / Q000473:pathology; D010280:Parathyroid Glands / Q000473:pathology; D010281:Parathyroid Hormone / Q000097:blood; D012720:Severity of Illness Index; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D014807:Vitamin D / Q000097:blood; D014808:Vitamin D Deficiency / Q000209:etiology*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D
keywords: 25OHD; CTG correlations; Calcium; Myotonic Dystrophy type 1; Myotonic Dystrophy type 2; PTH; Phosphate